Fuel delivery pump system for injection internal combustion engines



ySept 24, 19ML- J, F. JANSSEN v 2215,46?

FUEL.DELIVERY PUMP SYSTEM FOR INJECTION INTERNAL COMBUSTION ENGINEE Filed July 9, 1958 Patented Sept. 24, 1940 PATENT OFFICE FUEL DELIVERY PUMIP SYSTEM FOR INJEC- TION INTERNAL COMBUSTION ENGINES Johann Friedrich Janssen, Stuttgart, Germany,

assigner to Robert Bosch Gesellschaft mit beschrnkter Haftung, Stuttgart, Germany Application July 9, 193s, serial No.' 218,428 In Germany July 27, 1937 3 Claims.

livers fuel into the inlet chamber during operation.

The air contained in the pipes leading to the inlet chamber in the casing. of the injectionA pump and in the inlet chamber itself before the engine is started up is generally forced out by fuel before starting by actuation of the hand. pump. This air was hitherto conveyedaway to,- ward the supply container or on to the inlet sideof the delivery pump through a return pipe branching oif from the inlet chamber of the injection pump. The return pipe necessary for v this purpose is undesirable in many cases. However, according to the invention this return pipe can be completely discarded if there is provided, at about the highest point of the inlet chamber of the injection pump, a. narrow outlet leading to outside the delivery system, which outlet is open for at least such a time as air is forced out on hand pumping -by the fuel thus delivered, but closes automatically as a result of the pressure increase, which is produced, chiefly in operation by the delivery of the delivery pump, in the fuel-filled inlet chamber, after the air has been forced out of the inlet chamber.

The invention is more particularly described with reference to the accompanying drawing, in which:

Figure 1 shows the layout of a fuel delivery system according to the example of construc tion.

Figure 2 is a longitudinal section through the outlet valve, which is connected to the inlet chamber of the casing of the injection pump.

An injection pump I is connected through y the pressure pipes 2 tothe injection nozzles of an internal combustion engine (not shown). A fuel supply container 3 located remote from and arranged below the injection plant is connected through pipes 4a and 4b, in which cut-olf cocks 5 are disposed, to the suction side of two delivery pumps 6a and 6b. The pressure side of both delivery pumps is in connection through a pipe l with an air separator 8. The end of the pipe 'l connected to the air separator projects into the inner chamber of the air separator and opens below the lowest fuel level which can begreached in operation. This arrangement is desirable be- (Cl. 12S-139) cause it permits delivery of fuel to air separator 8 with little or no production of foam. A second pipe 9 connects the air separator 8 with the inlet chamber Ia of the injection pump I; it projects from above into the inner chamber `of the air separator. A float `II) carries, on the part projecting out of the fuel level, a pin I0a, of which the pointed free end `is constructed as a valve cone. To the upper part ofthe casing of the air separator opposite to this pointedend is lo connected a pipe III, -which opens into the air induction pipe I2 of the injection internal combustion engine.

In the suction pipe 4a of the delivery pump 6a is disposed a hand pump I3, the work chamber of which is connected in operation with the pipe la, so that `the fuel may pass from the supply container to the delivery pump. The suction and pressure sides ofthe delivery pump 6a are connected by a pipe I4, and in this pipe is provided a check or non-return valve I5 which opens towards the pressure side of the delivery pump. The suction and pressure sides of the delivery pump 6b are likewiseinterconnected by a pipe I6, a non-return valve Il opening towards the suction side of the delivery pump being provided.

At that end of the inlet chamber which is opposite to4 the'point of entry of the pipe 9 into the inlet chamber Ia of the injection pump there is provided in the casing of the injection pump an opening I8 which starts from the highest point of the inlet chamber. To this opening there is connected through a Valve I9 one end of a pipe 20, the other end of which opens into the pipe I I, which is connected with the induction pipe of the engine. As Figure 2 shows, the casing 2| of the valve I9 is provided with a blind bore and is secured to the casing of the injection pump, the outlet opening I8 of the inlet chamber 'opening into the blind bore. A mov' able piston valve 22 'is tightly fitted in the blind bore of the valve casing. Between the piston valve and the base of the valve casing is accommodated a helical spring 23, which tends to press the piston valve on to a seat in the vvalve casing provided on the left hand end of the bore ofthe casing. A longitudinal and cross. bore 24 disposed in the upper part of the piston valve opens, on one hand, at the piston face facing the inlet chamber and on the other hand at the upper superficies of the piston. In the upper wall of the valve casing is provided a bore 25, which opens into the-pipe 20, which is secured to the valve casing. A set-screw 26 provided in the Wall of the valve casing projects into'a longitudinal groove in the piston valve and prevents the valve from turning. A pin 21, which limits the displacement path, is provided at the right hand end of the piston valve.

When the engine is at a standstill, fuel can be withdrawn from the supply containers and delivered to the delivery pump 6a by means of the hand pump I3. As soon as a certain pressure is reached in front of the delivery pump, the check or non-return valve I5 opens on further actuation of the hand pump so that, bypassing the delivery pump, fuel is delivered through the pipe l to the pressure side of the delivery pump 6a, and into the air separator 8. 'Ihe air separator allows the air expelled from the pipes 4a, I4, 'I and also a part of the air forcedv out of .it by the fuel to escape until the valve cone, which is raised `beyond a certain level on the rising of the fuel level, covers the point at which the pipe Il opens into the air separator.

The fuel delivered further by the hand pump finally reaches the inlet chamber of the injection pump. 'Ihe air forced upwards when the fuel level rises higher cannot flow away to the induction pipe as long as the piston valve 22 keeps the pipe 20 closed. On further actuation of the hand pump, the pressure in the inlet chamber rises to such an extent that the piston valve is displaced to the right by this pressure into a position in which the mouth of the narrow bore 24 on the body of the valve 22 begins to open the hole 25, so that the air begins to flow to the induction pipe I2 through the pipe 20. Finally, on hand pumping, a pressure is reached at which the piston valve 22 occupies the position shown in Figure 2, in which the valve has completely opened the hole 25 and the connection between the inlet chamber and the pipe 20 and all the air can escape from the inlet chamber. When all the air has been expelled and fuel has been pressed into the narrow bore 24 by further actuation of the hand pump, the counterpressure opposed to the hand pump increases in a manner which can be felt, which is a sign that the inlet chamber is completely lled with fuel.

On the operation of the engine, the delivery pumps only deliver air-freed fuel into the inlet chamber of the injection pump. Since the narrow bore 24 opposes a considerable resistance to the passage vof the fuel, 4the pressure in the inlet chamber can rise considerably above the pressure attainable with the hand pump, by which the valve is then displaced further to the right into a position in which the narrow bore is closed by the inner wall of the casing and the pin of the valve bears on the stop.

I declare that what I claim is:

1. A fuel delivery pump system for injection internal combustion engines comprising an injection pumping apparatus consisting of a plurality of separate pumps, an inlet chamber common to all the separate pumps arranged in the casing of the injection pump, at least one hand pump for delivering fuel into said inlet chamber, when starting, at least one delivery pump delivering fuel into said chamber during operation, a narrow outlet provided at aboutthe highest point of the said chamber, opened for at least such time as air is displaced, by hand pumping, by the fuel thus delivered, and means to close said outlet automatically as a result of the pressure increase produced in the fuel lled inlet chamber, by delivery of the delivery pump after the air has been forced out of the inlet chamber.

2. A fuel delivery pump system for injection internal combustion engines comprising an injection pumping apparatus consisting of a plurality of separate pumps, an inlet chamber common to all the separate pumps arranged in the casing of the injection pump, at least one hand pump for delivering fuel into said inlet chamber, when starting, at least one delivery pump delivering fuel into said chamber during operation, a narrow outlet provided at about the highest point of the said chamber, opened for at least such time as air is displaced, by hand pumping, by the fuel thus delivered, and a control member in said outlet displaced by the pressure arising on hand pumping so that the air can escape from the inlet chamber, said control member operable to close said outlet when fuel is delivered thereto.

3. A fuel delivery pump system for injection internal combustion engines comprising an injection pumping apparatus consisting of a plurality of separate pumps, an inlet chamber common to all the separate pumps arranged in the casing of the injection pump, at least one hand pump for delivering fuel into said inlet chamber, when starting, at least one delivery pump delivering fuel into said chamber during operation, a narrow outlet provided at about the highest point of the said chamber, opened for at least such time as air is displaced, by hand pumping, by the fuel thus delivered, a passage in said outlet leading away from the inlet chamber, a piston valve in said passage, a spring loading said piston valve, and a restricted duct forming a throttle point in said piston which opens at the skirt of ber With the outlet merely as long as air has to be expelled from said chamber, butvwhich responds to an increased pressure of fuel, especially to fuel delivered during operation so that the outlet is closed by the pressure increase occurring in the said chamber when fuel isA delivered to said outlet.

J OHANN FRIEDRICH JANSSEN.

vthe piston and which connects the inlet cham- 

